Aims: Prevalence of unhealthy alcohol use and co-occurring mental health problems is high among persons living with HIV (PLWH) in sub-Saharan Africa (SSA). Yet, there is a dearth of evidence-based treatment options that can address both unhealthy alcohol use and comorbidities in SSA HIV care settings. Recent studies testing single-session alcohol brief interventions (BIs) among PLWH in SSA have suggested that more robust treatments are needed. This paper describes the protocol of a pilot randomized controlled superiority trial that will test the effectiveness of an evidence-based transdiagnostic multi-session psychotherapy, the Common Elements Treatment Approach (CETA), compared to a control condition consisting of a single session brief alcohol intervention (BI) based on CETA, at reducing unhealthy alcohol use, mental health problems, and other substance use among PLWH in urban Zambia. Methods: The study is a single-blind, parallel, individually randomized trial conducted in HIV treatment centers in Lusaka. 160 PLWH who meet criteria for unhealthy alcohol use + mental health or substance use comorbidities and/or have a more severe alcohol use disorder are eligible. Participants are randomized 1:1 to receive the single-session BI or CETA. Outcomes are assessed at baseline and a six-month follow-up and include unhealthy alcohol use, depression, trauma symptoms, and other substance use. Conclusions: The trial is a first step in establishing the effectiveness of CETA at reducing unhealthy alcohol use and comorbidities among PLWH in SSA. If effectiveness is demonstrated, a larger trial featuring long-term follow-ups and HIV treatment outcomes will be undertaken.